Background: Although tenotomy of the medial rectus (MR) is generally regarded to be obsolete, consecutive exotropia after this procedure, requiring a reoperation, still occurs.
Patients and methods: In 143 patients a reoperation after tenotomy of the MR had to be performed because of consecutive exotropia. Either only the MR was sutured at the original insertion (advancement; this constitutes group 1, n = 101) or the lateral rectus (LR) was recessed in addition (group 2, n = 12). The recession of the LR was only added if the adduction was not distinctly limited and if the distance of the MR from the limbus was less than 16 mm. We wanted to find out whether the procedure in group 1 or 2 gave the better results.
Results: In group 1 the muscle sheath of the MR was found at a distance of 7 mm (median), the muscle itself at a distance of 18 mm from the limbus (confidence interval 13.5-25 mm). In group 2 the distance of the muscle sheath from the limbus was similar to group 1, the muscle itself was found already at a distance of 12 mm from the limbus (confidence interval 6-18 mm). After reinsertion of the muscle at the original insertion without recession of the LR, a distinct limitation of abduction combined with a globe retraction was seen immediately after surgery. A spontaneous release of the old contracture reduced these troublesome side effects. Three months postoperatively the initial surgical effect had diminished to 83%. The average postoperative squint angle was -3 degrees at 5 m and -4 degrees at 0.33 m with a high scatter. In group 1 [group 2 in brackets], the range of the horizontal motility was improved by 15 degrees [10 degrees] (median) and the incomitance, i.e. the difference between the angle of squint at 25 degrees gaze to the right and to the left, by 4 degrees [0 degrees, i.e. no improvement]. Thus, this postoperative improvement was smaller in cases of simultaneous recession of the LR (group 2).
Discussion: The most important aim in a reoperation after tenotomy of the MR is to find the muscle itself and to suture it to the original insertion. It can be expected that the contracture of the MR will loosen when the muscle is put under increased tension. This effect will be less if the LR is recessed in addition to the advancement of the MR. Consistent with this assumption, our not randomized, retrospective study revealed a better horizontal motility after advancement of the MR alone. Because of the difficulties in revising a tenotomy, we strongly advise a graded recession rather than any form of tenotomy.